It is well known that endovascular endografts may be inserted into the human body during numerous medical procedures. Endografts are typically inserted into vessels and held in place by friction, such as with self-expanding or balloon expandable stents. The endografts may also be affixed to vessels with hooks, barbs or staples.
The endografts may be formed from synthetic materials, such as polyester, expanded polytetraflouroethylene (“ePTFE”), or others. The endografts may also be formed of natural vessels harvested from other areas of the body or from a donor mammal. Notwithstanding the various materials utilized, migration of the endografts over time remains a problem.
Caudad device migration, which refers to movement of an endograft away from the heart of a person, is known to lead to a Type 1 endoleak with aneurysm sac reperfusion, enlargement and rupture. Cephalad device migration, which refers to movement of an endograft toward the heart of a person, may lead to coverage of the renal artery orifices and renal insufficiency.
Such device migration is caused by many factors. One known factor is poor patient selection. Patients with cone shaped aortic necks, severe neck angulation, short necks or whose aortic necks have laminated thrombus present at the landing site are generally susceptible to device migration problems. Other device migration issues are caused by changing aortic morphology following device implantation including continuing aortic neck growth. Finally, migration may be caused by device structural fatigue and device design related issues. Device migration has been found even in cases in which these identified conditions do not exist.
Treatment of caudad migrations have traditionally been conducted by the addition of “sleeves” to the proximal end of the endograft in an effort to regain purchase between the endograft and the vessel to which it is attached in order to maintain a seal between the two. More drastic options include resorting to conventional surgery. These late conversions are, unfortunately, associated with an unacceptably high mortality rate.
Treatment options for the cephalad migrations are even less attractive. In the face of continued migration, resignation may be the only option as such migration may lead to renal insufficiency requiring hemodialysis. To permit device removal, a typical conversion in this case involves supra-celiac aortic cross-clamping, and its associated problems.
Prior attempts at fixation of migrating devices, including additions of hooks, barbs, supra renal stents and other fastening devices have proven to be insufficient. Some conventional endovascular stapling devices have been described which fire or discharge one staple at a time requiring removal and reinsertion or repositioning of the devices multiple times to secure an endograft to a vessel. It would therefore be advantageous to provide an endovascular stapling device which may be used to adequately arrest existing migrations, as well as secure new endografts in a manner likely to eliminate future migration. Actual fixation of the endograft to the aortic neck with closed staples at multiple points will also prevent the aorta itself from enlarging as the aorta is forced to conform to a prosthetic graft with a predetermined maximum diameter.